Vegetable oils are generally pressed or extracted oil from a vegetable source. Vegetable oils can contain phospholipids, commonly known as gums, which can be hydratable or non-hydratable. For example, the following oils can contain gums, in weight percent, soybean 1 to 3, corn 0.6 to 0.9, sunflower oil 0.5 to 0.9 and canola oil (crude) 1 to 3. Gums can be partially removed from vegetable oils through know degumming processes, such as water degumming, acid degumming, caustic refining and enzymatic degumming. Such processes can be found in U.S. Pat. Nos. 4,049,686; 5,239,096; 5,264,367; 5,286,886; 6,001,640; 6,033,706; 7,494,676 and 7,544,820. Further references include U.S. Pat. App. Pub. Nos. 2007/0134777; 2008/0182322 and 2012/0258017.
Other degumming processes include high shear mixers, for example, the processes disclosed in U.S. Pat. Nos. 4,240,972; 4,698,185; 6,172,248 and 8,491,856. It has been proposed to refine vegetable oil using cavitation, such as that disclosed in U.S. Pat. App. Pub. Nos. 2009/0314688; 2011/0003370 and 2014/0087042.
The existing methods are not sufficient to efficiently remove non-hydratable phospholipids present in the oil because the non-hydratable phospholipids are not available to be hydrated or reacted to enable their removal. Thus, there is a need for alternative degumming processes for treating vegetable oil that can provide cost-effective removal of phosphorous, preferably to levels of 5 ppm to 10 ppm or below, depending on applications, and of metallic impurities such as calcium, magnesium and/or iron. The present invention focuses on such process for degumming vegetable oils.